Q: To stop a download on Mac (of Mac OS sierra)

In the app store, go to the purchases menu and hold the option key in the keyboard while clicking on the pause button, it will turn into cancel while you press the option key.

Eib.

Hi Eib,

I didn't see sierra anymore on app store, but still exist on launchpad. I've try to hold option while clicking the icon then chose delete, but it still continue the downloading.

Thank You

You need to open the app store app, then choose "Purchased" icon from the top of the app. It will list your purchases.  Then do as EiberEloy said to cancel the download.

Thanks a lot EiberEloy that worked great.